The invention relates to a copying machine comprising a deflecting device which causes a deflection of an arriving sheet by approximately 180.degree. and which is arranged directly behind a withdrawal roller assigned to a fed stack of sheets.
In the case of known arrangements disclosed, for example, in the Japanese Patent Document JP-PS 64-6508 and the German Patent Document DE-OS 31 36 206, guide ducts, which are bent in a U-shape and through which the copying paper is moved, are used as deflecting devices. For this known type of deflection, comparatively large radii of curvature are required since otherwise the front edge of a sheet can no longer easily slide in the feeding duct which would result in a buckling of the sheet and therefore in a jamming of the paper. This difficulty with radii of curvature of the guide ducts which are too small would occur mainly in the case of heavy types of paper and in the case of foils.
It is an object of the invention to equip a copying machine at low expenditures with a space-saving deflecting device which permits a reliable deflecting of a sheet without disturbances and with a comparatively small radius of curvature.
For a copying machine of the initially mentioned type, this object is achieved in that the deflecting device is constructed as a guiding element which partially surrounds the withdrawal roller and which rests with a predetermined contact force on the circumference of the withdrawal roller.
In the case of this construction, a withdrawn sheet is not only passively deflected by walls of the introducing gap but, by means of a pressing against the withdrawal roller, is actively drawn by it around the deflection. This ensures a secure and reliable transport of a sheet, specifically also when a deflection is desirable within a small area, for reasons of a saving of space, thus with a considerable curvature. The arrangement according to the invention permits a radius of curvature of less than 20.5 mm for the deflection for example; and thus is a very flat construction.
In a further development of the invention, a leaf spring which is prestressed in a holding device resting against the withdrawal roller circumference and held in the circumferential direction, or a teflon strip is used as the guiding element. The slight sliding friction coefficient of this material facilitates the paper transport. At the same time, the use of the leaf spring or of the teflon strip as the elastic element combines favorable elasticity properties with low manufacturing expenditures.
In a further development of the invention, devices are provided for adjusting the contact force of the guiding element. As a result, the deflecting device of the copying machine can be adapted with minimal effort to the paper types or foil types to be drawn in.
In a further development of the invention, the copying machine comprises a sensor inside the transport area arranged behind the withdrawal roller as well as a coupling coupled with the sensor and arranged on a shaft of the withdrawal roller. By means of the sensor, the position of the drawn-in sheet can be recognized. By means of a corresponding signal of the sensor, it is possible to actuate the coupling and thus guide the withdrawal roller into a predetermined position. A flattening on the withdrawal roller can therefore, before the drawing-in of a new sheet, always be brought into the area which is opposite the front edge of the stack of sheets in order to permit a feeding of individual sheets, as required, particularly for the feeding of a foil.
In a further development of the invention, the coupling comprises a rod which can be moved between two positions and a hub which is non-rotatably fastened on the shaft of the withdrawal roller and has a ring groove provided on one side, in which case the rod which engages in the ring groove of the hub, in each case, in an end position, interacts on one side with catches on the inner edge of the ring groove and interacts on the other side with a single catch on the outer edge of the ring groove. By means of the single catch on the outer edge, a defined position of the withdrawal roller can be adjusted by means of this coupling, while, in contrast, by means of the catches on the inner edge of the ring groove, the shaft for the withdrawal roller can be arrested and thus the paper transport can be stopped in any desired position.
In a further development of the invention, the inner edge of the ring groove of the hub has no catches within an angular area situated opposite the single catch on the outer edge of the ring groove. This measure has the purpose of preventing an unintentional stopping of the shaft when the rod is moved into that position which permits a no-contact turning past of the individual catch on the outer edge of the ring groove. This is mainly expedient when, for the drawing-in of a single sheet of paper, the withdrawal roller carries out several rotations because of its comparatively small radius. The single catch must then, in a no-contact manner, be turned past the nose of the rod so many times until the sheet of paper is completely drawn in or moved along. The latter can be recognized by the pertaining sensor. It is only then that the rod is moved into the position in which its nose can interact with the single catch. The resting of the catch against the nose will then lock the shaft and ensure the correct position of the withdrawal roller for another drawing-in of paper.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.